1. Field of the Invention
The present invention relates to a vibrating gyroscope and angular velocity sensor, and more particularly, to the construction of a vibrating gyroscope having a greatly reduced height, and to the construction of an angular velocity sensor having the vibrating gyroscope.
2. Description of the Related Art
Up to now, in navigation systems and car body control systems used in cars, since it is required to confirm the yaw direction of a car, that is, the turning direction of the body of the car, a rotational angular velocity about the vertical axis perpendicular to the traveling surface (ground) is detected. To detect the rotational angular velocity, an angular velocity sensor equipped with a vibrating gyroscope is utilized, and such a vibrating gyroscope generally contains a pole or tuning-fork vibrator (see Japanese Unexamined Patent Application Publication No. 8-292033 and Japanese Unexamined Patent Application Publication No. 10-307029).
Furthermore, the angular velocity sensor equipped with a vibrating gyroscope for detecting a rotational angular velocity is also utilized for correcting video camera vibrations due to hand vibration, and, rotational angular velocities about two axes perpendicular to each other on the plane parallel to the CCD surface are detected by vibrating gyroscopes.
The above-described angular velocity sensor of the related art is generally disposed inside a car so as to be parallel to the traveling surface, and accordingly, the mounting plate on which the vibrating gyroscope is mounted is also disposed to be parallel to the traveling surface. On the other hand, a pole or tuning-fork vibrator with which the vibrating gyroscope is equipped can detect the rotational angular velocity acting around an axis (detection axis) that is parallel to the longitudinal direction of the vibrator.
Accordingly, when the vibrating gyroscope according to the related art is mounted on the mounting plate disposed parallel to the traveling surface, it is required to mount the vibrator such that the longitudinal direction of the vibrator is perpendicular to the mounting plate. However, when constructed in this way, there is a problem in that only the vibrating gyroscope equipped with a vibrator with a large length protrudes more than other parts on the mounting. Moreover, it can be also considered to reduce the overall length of the vibrator in the longitudinal direction. However, if the overall length of the vibrator is reduced, since the resonance frequency increases and the sensitivity and SN ratio are deteriorated, it becomes impossible to detect the rotational angular velocity with a high degree of precision.
Furthermore, when involuntary movements of a person's hands during use of a video camera are corrected by using the vibrating gyroscope according to the related art, if the mounting surface of the main board is perpendicular to the CCD surface, since the longitudinal direction of a vibrator with which the vibrating gyroscope is equipped is required to be perpendicular to the main board of the camera, the vibrating gyroscope protrudes more than other parts. Moreover, although it has been considered to make a board on which the vibrating gyroscope is mounted separated from the main board and to make wiring connections by using a flexible printed circuit board, etc., such a construction increases the number of parts and becomes complicated, and as a result, an increase in cost is inevitable.